Overview
EN ISO 6506-3:2014 - “Metallic materials - Brinell hardness test - Part 3: Calibration of reference blocks” specifies the method for calibrating Brinell hardness reference blocks used in the indirect verification of Brinell hardness testing machines. Prepared by ISO/TC 164 and adopted by CEN, this part of the ISO 6506 series defines the procedures needed to ensure metrological traceability, measurement reproducibility and documentation for reference blocks used in hardness quality control.
Key topics and technical requirements
- Scope and traceability
- Calibration method for reference blocks used with Brinell hardness testing machines (see ISO 6506‑2 for machine verification).
- Requirements to ensure traceability of the calibration machine to the SI.
- Manufacture and physical requirements
- Blocks must be specially manufactured for reference use and free of magnetism (steel blocks should be demagnetized).
- Minimum thickness: 16 mm for 10 mm balls, 12 mm for 5 mm balls, 6 mm for smaller balls (with noted exceptions).
- Surface flatness, parallelism and roughness (Ra) requirements are specified (Table 1).
- Calibration machine and verification
- Calibration machines must meet ISO 6506-2 general requirements plus additional clauses (force, indenter, measuring device).
- Direct verification of the calibration machine at intervals not exceeding 12 months, including force and indenter checks.
- Force measurements: minimum three readings (elastic proving device ISO 376 class 0.5 or better); mean must agree within ±0.1% of nominal.
- Measurement system requirements
- Indentation diameter measuring system resolutions: 0.002 mm for 5 mm and 10 mm ball indentations; 0.001 mm for